1. Field:
The present disclosure relates generally to systems and methods for analyzing aerodynamic effects of features in the surface of a vehicle. More particularly, the present disclosure relates to systems and methods for designing, making, and verifying the reworking of inconsistencies in thermal protection systems for aerospace vehicles by calculating cross flows over the surfaces of such vehicles.
2. Background:
Aerodynamic heating is the heating of a solid body produced by frictional interactions with the passage of fluid about the body. For example, aerodynamic heating occurs when air passes over an aerospace vehicle, such as a spacecraft or aircraft, during vehicle transit, ascent, descent, and reentry. In this case, aerodynamic heating of the vehicle is a function of various parameters, such as reentry angle, vehicle speed, air density, and vehicle configuration, among other parameters. Another parameter affecting aerodynamic heating of an aerospace vehicle is the thermal protection system materials that are used to protect the vehicle from aerodynamic and other heating. For example, depending on the vehicle configuration and thermal protection system material properties, aerodynamic heating typically increases as the air surrounding the vehicle increases in density and as the air passes more quickly over the vehicle. An increase in the speed at which air passes over a vehicle typically occurs as the speed of the vehicle increases.
Aerodynamic heating considerations may have many effects on aerospace vehicle design and operation. For example, aerodynamic heating may affect the performance of an aerospace vehicle. The thermal protection system configuration and materials that are needed for a vehicle may be based on the levels of aerodynamic heating expected to be experienced by the vehicle during operation. Aerodynamic heating actually experienced by an aerospace vehicle during operation may affect how often inspections and maintenance are needed. Levels and durations of aerodynamic heating experienced during vehicle operation may affect whether the vehicle should be reconfigured, reworked, or replaced.
A vehicle thermal protection system may be used to reduce or control the effects of aerodynamic heating on an aerospace vehicle structure to within acceptable limits. For example, an aerospace vehicle may be a vehicle that travels at supersonic, hypersonic, exo-orbital, and exoatmospheric speeds, and a spacecraft that reenters the atmosphere. A thermal protection system for such an aerospace vehicle may include a barrier to protect the vehicle from aerodynamic heating when the vehicle renters the atmosphere. For example, the thermal protection system may include material that covers the surfaces of the vehicle that are exposed to air during reentry. Examples of materials that may be used for a vehicle thermal protection system include silica glass fiber materials, ceramic matrix composite (CMC) materials, polymeric matrix composite (PMC) materials, and other materials, as well as such materials that may be clad with ablative, high-temperature resistant, or other coating materials.
A space shuttle is an example of an aerospace vehicle. On a space shuttle, most of the thermal protection system takes the form of tiles that are attached to the surfaces of the vehicle that are exposed to aerodynamic heating during reentry. For example, these tiles may be located on the lower surface of the space shuttle, among other suitable places thereon. The tiles on the space shuttle are made of an insulating material known to those having knowledge in the relevant arts to be a silica glass fiber material. The insulating tiles absorb and radiate heat, while minimizing heat load conduction to the aluminum airframe of the space shuttle.
Inconsistencies may occur in the thermal protection system tiles of a space shuttle, in the materials used to attach the tiles to the shuttle surface, and in materials used to seal and fill gaps and channels between the tiles. Inconsistencies may include nicks, dings, scrapes, or what those skilled in the art may refer to generally as cavities, in the surface of the thermal protection system tiles. Inconsistencies also may include material that becomes lodged between tiles of the thermal protection system. Such inconsistencies may be referred to as gap fillers by those skilled in the art. Inconsistencies in a vehicle thermal protection system may arise or occur during pre-flight preparation, as well as during operation of an aerospace vehicle, such as the space shuttle. Such undesirable inconsistencies may affect the aerodynamic characteristics of the tiles and, therefore, may affect performance of the space shuttle thermal protection system. Similar issues may arise in other types of thermal protection systems that are used in other types of aerospace vehicles and in thermal protection systems that may employ other thermal protection system materials, such as ceramic matrix composite materials, polymeric matrix composite materials, or other materials.
Accordingly, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.